import math

x = input()
y = input()
l = input()
turn = 0
x = int(x)
y = int(y)
l = int(l)

if int(x) >= 0:
	if int(y) != 0:
		turn = 1
	else:
		turn = 0
else:
	turn = 2
	
print(math.ceil(abs(x)/l)+math.ceil(abs(y)/l)+turn)